This invention constitutes an improvement over U.S. Pat. No. 4,302,941 granted to T. L. DuBell on Dec. 1, 1981, entitled "Combustion Liner Construction for Gas Turbine Engine" and U.S. Pat. No. 4,512,159 granted to R. L. Memmen on Apr. 23, 1985, entitled "Clip Attachment", both of which are assigned to United Technologies Corporation, the same assignee as this patent application. FLOATWALL.RTM. combustor wall includes an outer shell which may be formed in a complete hoop or segmented and has attached thereto a plurality of free floating panel segments positioned radially inward from the shell and adapted to shift in response to the thermals and vibratory forces of the system. Such designs are capable of withstanding the hostile environment which they are subjected with high durability characteristics.
The problem inherent in the FLOATWALL.RTM. combustor design is the attachment of the floating wall panel segments to the outer shell. One such scheme used heretofore is forming a hook integral with the segmented FLOATWALL.RTM. panel that passes through an aperture in the outer shell to which is attached a strap. Such a system is relatively complex and expensive.
The prior art U.S. Pat. No. 4,512,159 contemplates attaching the FLOATWALL.RTM. panel segments by a spring clip adapted to fit onto an integral post so as to preload the panel segment toward the shell. Since the clips are removable without damage to the post, the removal of panel segments is facilitated which enhances the maintainability of the combustor. This type of clip has a spring portion that supports the panel segment, and experience has shown that such spring clips tend to lose their ability to preload after a relatively short operating time and must therefore be replaced. The clips lose their ability to preload because the stress in the spring portion caused by the preload is relatively high as compared to the deflection in the spring portion caused by that preload. Put another way, the "spring rate" (the ratio of stress to deflection) of the spring clip is too great, causing the spring portion of the clip to permanently deform instead of simply flexing. Although some permanant deformation of the spring portion can occur without impairing the preloading function of the clip, once excessive deformation of the spring portion occurs, the clip loses its ability to preload the panel segment and must be replaced.
What is needed is an attachment clip that provides the benefits of the prior art clips and is less subject to losing its preload capability during use.